Automated or robotic power tools such as robotic lawnmowers are becoming increasingly more popular. In a typical deployment, a work area, such as a garden, is enclosed by a boundary cable with the purpose of keeping the robotic lawnmower inside the work area. The robotic lawnmower is typically also configured to communicate with a charging station located in the work area and connected to the boundary cable.
Using standardised coding such as Gold codes, has the obvious advantage that new coding schemes need not be invented. However, the inventors have realized that the frame length commonly used for CDMA coding, such as Gold coding, when used with technology commonly used for lawnmower systems leads to a transmission time for the entire frame that is in the order of seconds, such as 1 second, 0.5 seconds or up to 0.5 seconds. Such time spans may be unpractical in real life implementations as a robotic lawnmower operating using such time frames would move a distance that could not be neglected before being able to decode the entire frame. The robotic lawnmower may thus be rendered unable to detect whether it is still within the work area or not.
This would for practical reasons render gold coding inoperable for robotic lawnmower systems. To overcome this, the inventors realized that by dividing a frame as per above, shorter segments of the entire frame, i.e. sub frames, may be used to control the robotic lawnmower.